The invention relates to novel antitussive and antihistaminic tannate compositions. The compositions contain as essential ingredients carbetapentane tannate and chlorpheniramine tannate.
A considerable number of tannic acids occur in nature. Chemically, these acids are described as polymers of different hydroxybenzoic acids. Generally, when the term tannic acid is employed, as in the present case, the acid referred to is gallotannic acid, the internal ester of gallic acid also frequently referred to as tannin.
Tannic Acid consists of an amorphous powder glistening scales or spongy masses varying in color from yellowish-white to light brown. Tannic acid is very soluble in water, glycerine or alcohol.
Tannic acids are usually obtained from glycosides which consist of several molecules of a tannic acid in combination with glucose.
Commercially available, tannic acid, also known as Tannin, has a complex non-uniform chemistry usually contains from about 5% to about 10% by weight water, has a molecular weight of about 1700 and is typically produced from Turkish or Chinese nutgall.
Carbetapentane, known chemically as, 2-(2-diethylaminoethoxy)ethyl-1 phenylcyclopentane carboxylate is an antitussive compound that is described in U.S. Pat. No. 2,842,585 and is structurally related to caramiphen. Carbetapentane citrate has a melting point of 93xc2x0 C. and occurs as a white powder freely soluble in water and slightly soluble in alcohol.
Carbetapentane has an atropine-like action that depresses the cough reflex by selective central nervous system depression.
Chlorpheniramine, known chemically as 3-(p-chlorophenyl)-3-(2-pyridyl)-N,N-dimethylpropylamine, is a synthetic optically active d-isomer resolved from dl racemates of the amine by treating said racemate with an optically active d- or I-isomer of the substituted succinic acid in the presence of a non-reactive compatible organic solvent to cause the formation of the corresponding diasteroisomeric salts thereof, separating the salts so obtained by fractional crystallization, and releasing the desired d-isomers from the separated amine salts as more fully described in U.S. Pat. No. 3,061,517
Chlorpheniramine maleate salt has a melting point of 130-135xc2x0 C. and is slightly soluble in benzene and ether.
Antitussive and antihistamine compounds in the form of their free bases as well as their salts, e.g. hydrochloride, citrate, maleate, tannate, etc., are well known. Antitussives and antihistamines in the form of their tannate salts are very desirable because such salts are generally stable and may be combined in such form without any untoward side effects.
Antitussives and antihistamines in the form of their tannate salts are typically prepared by reacting the free base, e.g. carbetapentane, chlorpheniramine, etc. with tannic acid in the presence of a volatile solvent, usually isopropanol. Typically, in the conventional isopropanol route, the antitussive or antihistaminic free base and the tannic acid will be present in the isopropanol at a concentration of about 20% based on the weight of the reaction mixture. The reaction mixture is stirred for about one hour while maintaining the mixture at 60-70xc2x0 C. The reaction mixture is cooled to room temperature and then filtered, washed with isopropanol and then vacuum dried. Alternative routes to the tannate salts are described in U.S. Pat. Nos. 5,599,846 and 5,663,415.
It has now been found that the novel combination of carbetapentane tannate and chlorpheniramine tannate produces a composition having antitussive and antihistaminic properties superior to the use of either one of the tannate compounds alone.
The compositions of the present invention may be prepared for oral administration in the form of powders, capsules, elixirs, syrups and the preferred forms of tablets formulated so that ideally each tablet contains about 50 mg to about 75 mg, preferably about 60 mg of carbetapentane tannate and about 2.5 mg to about 7.5 mg, preferably about 5.0 mg chlorpheniramine tannate or suspensions formulated so that ideally each 5 mL (approximately 1 teaspoon) of suspension would contain approximately 20 to 30 mg carbetapentane tannate preferably about 30 mg of carbetapentane tannate and about 2.0 mg to about 6.0 mg, preferably about 4.0 mg chlorpheniramine tannate.
Tablets containing the unique tannate combination of the present invention are prepared in a conventional manner by the addition of suitable pharmaceutical carriers including fillers, diluents, colorants, lubricants and the like as well as conventional and well known binding and disintegrating agents. A typical tablet composition of the present invention containing starch, dibasic calcium phosphate, coloring, magnesium stearate, methylcellulose, polygalacturonic acid, povidone and talc as described in Example 1 which follows is prepared by well known conventional tabletting techniques such as those disclosed in U.S. Pat. Nos. 3,018,221; 2,798,024 and 2,757,124.